| Invoking a collection method with the same collection as the argument is likely | |
| incorrect. | |
| * `collection.addAll(collection)` may cause an infinite loop, duplicate the | |
| elements, or do nothing, depending on the type of Collection and | |
| implementation class. | |
| * `collection.retainAll(collection)` is a no-op. | |
| * `collection.removeAll(collection)` is the same as `collection.clear()`. | |
| * `collection.containsAll(collection)` is always true. |